Tel-Tru meat and pocket therms anyone?

Hey gang I was thinking of ordering a pocket therm and meat therm from Tel-Tru, they can be calibrated if they go out. At about $25 or $30 I figured the calibration was worth it, they're bi-metal analog therms. Wondering if anyone had any experience with them and if they are reasonable at their speed or just too slow.

I think the meat therm is left in the meat while it cooks, it has a glass window and can be ordered in 1.75" or 2" dials and 5" or 8" probes.